[PATCH] drm/i915/display: Workaround for odd panning for planar yuv

[Kandpal, Suraj]

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of
> Nemesa Garg
> Sent: Monday, September 30, 2024 4:54 PM
> To: intel-gfx at lists.freedesktop.org
> Cc: Garg, Nemesa <nemesa.garg at intel.com>
> Subject: [PATCH] drm/i915/display: Workaround for odd panning for planar
> yuv
> 
> Disable the support for odd x pan for even xsize for NV12 format as
> underrun issue is seen.
> 
> WA: 16024459452
> 
> v2: Replace HSD with WA in commit message [Suraj]
>     Modified the condition for handling odd panning
> 
> v3: Simplified the condition for checking hsub
>     Using older framework for wa as rev1[Jani]
> 
> v4: Modify the condition for hsub [Sai Teja]
>     Initialize hsub in else path [Dan]
> 
> v5: Replace IS_LUNARLAKE with display version.
>     Resolve nitpicks[Jani]
> 
> Signed-off-by: Nemesa Garg <nemesa.garg at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_atomic_plane.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> index e979786aa5cf..e3401a4f7992 100644
> --- a/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> +++ b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> @@ -1029,6 +1029,14 @@ int intel_plane_check_src_coordinates(struct
> intel_plane_state *plane_state)
>  		 * This allows NV12 and P0xx formats to have odd size
> and/or odd
>  		 * source coordinates on DISPLAY_VER(i915) >= 20
>  		 */
> +		/*
> +		 *  Wa_16023981245 for display version 20.
> +		 *  Do not support odd x-panning for even xsize for NV12.

Only mention WA no here the rest anyone can refer to by going and checking the HSD 

> +		 */
> +		if (DISPLAY_VER(i915) == 20 && fb->format->format ==
> DRM_FORMAT_NV12 &&
> +		    src_x % 2 != 0 && src_w % 2 == 0)
> +			return -EINVAL;

Also rather than return -EINVAL here we set hsub =2 and vsub =1 this should make sure odd panning is disabled
When we have even size since we only need to disable odd panning according to hsd not even panning this return may end
stop panning for even sizes all together.

Regards,
Suraj Kandpal
> +
>  		hsub = 1;
>  		vsub = 1;
>  	} else {
> --
> 2.25.1